This invention relates to dispensers, and more particularly, to dispensers for discharging material under pressure.
In the prior art, basically three different types of dispensers for discharging material are provided. These include: aerosol devices utilizing chemical propellants to pressurize and discharge the material; trigger operated mechanical discharge means wherein a pivoted trigger or lever is connected with a piston or plunger to obtain intermittent discharge or squirts of material; and finger operated pumps wherein a plunger is depressed with the finger to obtain intermittent discharges or squirts of the material.
All of these devices have one or more more disadvantages. For example, aerosol devices utilizing chemical propellants are being banned because of their potential harm to the environment. Moreover, these devices require specially constructed containers built to withstand high internal pressure, and the chemical propellants are not compatible with many materials desired to be dispensed. Additionally, there is considerable danger in handling and disposing of aerosol devices utilizing chemical propellants because of the pressures and explosive materials involved, and special precautions must be observed when filling aerosol containers utilizing chemical propellants.
The trigger operated dispensers and finger operated pump dispensers both eliminate the dangers inherent with chemical propellants, but are relatively difficult to operate and only a single short burst or discharge of the material is obtained with each manipulation of the actuator. The action required to operate such devices, and particularly the pump or plunger type devices, results in spray inaccuracy and finger fatigue.